Multilayered ceramic substrate and method of manufacturing the same

Abstract

A multilayered glass-ceramic substrate using copper as wiring material is fabricated by a step of forming wiring patterns with Au paste for connection of semiconductor chip prepared by adding at least one of Ni powder, Pt powder and Pd powder to Au powder, and copper oxide paste mainly composed of CuO powder, on a green sheet, and burning out the organic pattern by heat treatment in air, a step of reducing the copper oxide electrode by heat treatment in a reducing atmosphere containing hydrogen, and a step of sintering the substrate material, copper oxide electrode and gold electrode by heat treatment in nitrogen. Since the Au wiring pattern is formed on the top layer of the multilayered substrate in this constitution, wire bonding of high reliability is realized. Besides, by making use of the excellent solderability of Au, it may be also applied in flip-chip mounting of semiconductor. In addition, in this Au paste composition, the melting point of Au may be raised, and alloying or fusing is avoided if sintered at 900 DEG C. together with Cu electrode.

What is claimed is: 
     
       1. A method of manufacturing a multilayered ceramic substrate comprising the steps of: preparing a CuO paste comprising an inorganic component which comprises CuO powder, and an organic vehicle which comprises an organic binder and a solvent;   preparing an Au paste comprising an inorganic component which comprises 90.0 to 99.5 wt. % of Au powder and 0.5 to 10.0 wt. % of at least one of Ni powder, Pt powder and Pd powder, and an organic vehicle which comprises an organic binder and a solvent;   preparing a plurality of glass-ceramic green sheets each having via holes;   forming a pattern of said CuO paste on a surface of each of the plurality of glass-ceramic green sheets and a pattern of said Au paste on a surface of one glass-ceramic green sheet among the plurality of glass-ceramic green sheets such that the pattern of said Au paste is in contact with a part of the pattern of said CuO paste on said surface of said one glass-ceramic green sheet and filling the via holes of the plurality of glass-ceramic green sheets with said CuO paste;   laminating the plurality of glass-ceramic green sheets having formed thereon the patterns of said CuO paste and said Au paste so as to form a multilayer body such that said surface having formed thereon both the patterns of said Au paste and the pattern of said CuO paste becomes an outermost surface of said multilayer body;   heating said multilayer body in air so as to burn out the organic binder in each of said CuO paste and said Au paste;   heat treating said multilayer body in a reducing atmosphere containing hydrogen so as to reduce CuO in said CuO paste to a metal Cu; and   sintering said multilayer body in nitrogen to thereby form a multilayered ceramic substrate having inner Cu electrode patterns and on its outermost surface a Cu electrode pattern and an Au electrode pattern which is in contact with a part of the Cu electrode pattern.   
     
     
       2. The method according to claim 1, further comprising a step of mounting a semiconductor chip on said Au electrode pattern by a wire bonding method. 
     
     
       3. The method according to claim 1, further comprising a step of mounting a semiconductor ship on said Au electrode pattern by a flip-chip mounting method. 
     
     
       4. The method according to claim 1, wherein said Au paste further comprises at least one of metal oxide powder and glass powder.